1. Field of the Invention
The present invention relates to spectrometry, and more specifically, it relates to solid, liquid and gas sensors.
2. Description of Related Art
A variety of different molecules (solid, liquid and gas) can absorb energy at specific wavelengths of light. The resulting energy increase by the optically excited gas molecules may dissipate via collisions between the excited molecules and the surrounding molecules present, ultimately transferring the energy from vibration to translation. If the optical excitation source is pulsed, this results in periodic local heating the molecules, which induces a pressure change. The pressure change induces an acoustic wave which can be detected using a microphone. As different molecules absorb energy at different wavelengths, optically scanning a variety of different wavelengths allows identification of the molecules present based on the wavelengths at which an acoustic wave is detected. This technique has been used in large scale sensing apparatuses; however, a successful sensor fabricated on a micro-scale has not been achieved.